FOUS30 KWBC 060822
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
422 AM EDT Sat Jul 6 2024

Day 1
Valid 12Z Sat Jul 06 2024 - 12Z Sun Jul 07 2024

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS MUCH OF THE
CAROLINAS AND THE HAMPTON ROADS OF VIRGINIA...

...Southern states and Eastern Seaboard...

A cold front will be pressing east through New England while the 
trailing portion moves through the Eastern Seaboard, Southeast and
near the Gulf Coast. This slow moving boundary will be the focus 
for areas of heavy rainfall across the Gulf Coast region and much 
of the East Coast. An expansive Marginal Risk area spans from New
Mexico east to northern Florida and north to Maine.

A Slight risk was maintained across portions of Georgia, the 
Carolinas and into southeast Virginia. An impressive overlap of 
instability and moisture is noted across this region...with CAPE 
likely over 2000 j/kg and PWs around 2.25" (approaching 
climatological 95th percentile values). Scattered amounts of 3
inches will be possible along the I-95 corridor and vicinity.

Along the Gulf Coast and into Texas higher PW values will be 
streaming/pooling over the west-east orientated, slow moving front 
thus increasing the potential for higher rainfall rates within the 
isolated to scattered convection. Enough instability and moisture 
over eastern NM to suggest another round of terrain influenced 
diurnal convection is likely.

...Plains...

A mid-level shortwave is expected to dig south within the long 
wave trough over the central U.S. Although modest moisture will be
present, there will be support for broad ascent and increased 
forcing to suggest the potential for heavy rainfall rates of 1 to 2
inches/hr across the region. A Marginal Risk remains in effect from
eastern Dakota and western Minnesota, Iowa, northwest Missouri,
portions of Nebraska, Kansas, northeast Colorado, and the Oklahoma
and Texas Panhandles.

Campbell


Day 2
Valid 12Z Sun Jul 07 2024 - 12Z Mon Jul 08 2024

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF
KANSAS, OKLAHOMA, AS WELL AS THE CENTRAL AND SOUTHERN COAST OF
TEXAS...

...Coastal Texas and Louisiana...

The latest guidance and NHC forecast track for Beryl has trended
further north/east from the previous forecast. That positions Beryl
just offshore South Texas with the bulk of its precipitation 
shield hugging the Southeast Texas Coast and into southern 
Louisiana. This track adjustment prompted an expansion of the 
Slight Risk to the Houston Metro and the Marginal Risk to include 
southwest Louisiana. The storm motion and compact storm structure 
is forecast to keep the heaviest precip focused along the coast.
The latest guidance continues to favor higher QPF along and points
right of the storm track. There is still some uncertainty in the 
northern extent of the track as some guidance continues to fall 
even further north of the current forecast, so this forecast is 
subject to shifts in the exact location of the Slight and Marginal
Risk areas, but likely still confined to the coastal plain.

...Southern and Central Plains...

Organized convection is likely over portions of KS and OK Sunday
into Sunday night. Quite the impressive model QPF signal...with
both good run to run continuity and model to model agreement. Thus
forecast confidence is above average with this event. Interestingly
the pattern appears to favor a rather progressive convective
complex...and PWs are not forecast to be overly high either. Thus
the impressive QPF from the models, while somewhat surprising, is
likely indicative of the very strong mid/upper level forcing and
low level frontal convergence in play. A look at layer IVT suggests
we may start to see some low level connection to the moisture plume
ahead of Beryl, so this is certainly something to keep an eye on
and could act to enhance rainfall efficiency. Either way this is a
solid Slight risk, with the apparent progressiveness of convection
keeping the risk from going higher...but will need to continue to
monitor.

...Southeast...

With the stalled front across the region convection is expected to
persist, maintaining an isolated threat for flash flooding 
concerns. PWs will remain above the climatological 90th 
percentile, and layered IVT suggest we may see some mid/upper level
moisture connection to Beryl. The intrusion of tropical moisture
may help bolster rainfall efficiency in what will already be a 
favorable environment for heavy rainfall rates. A Marginal Risk
remains in effect from southern Alabama to northern Florida and
north to southeast Virginia. 

Campbell


Day 3
Valid 12Z Mon Jul 08 2024 - 12Z Tue Jul 09 2024

...THERE IS A MODERATE RISK FOR EXCESSIVE RAINFALL ACROSS PORTIONS
OF EASTERN TEXAS...

The National Hurricane Center has Beryl forecast to make landfall
during this period somewhere up the coast from Corpus Christi,
although the forecast track is subject to further adjustments. The
guidance continues to suggest a fairly compact storm therefore the
QPF swath is expected to be relatively narrow as the storm lifts
northward across eastern Texas. The highest QPF amounts will still
follow the track or slightly east of the path through this period.
Areal average of 3 to 7 inches can be expected with maximums
climbing into the double digits. A Moderate Risk was raised for
this period from Coastal Texas into eastern Texas. A Slight Risk
spans the coastline from south of Corpus Christi to east of Lake
Charles and northward into southwest Arkansas. A Marginal Risk
covers from South Texas to central Louisiana and from the
Texas/Oklahoma Panhandles to Southern Missouri. The placements of
the Excessive Risk areas will largely be dependent on the NHC track
so stay tuned for future adjustments.

...Southeast...

Convection will persist near the stalled frontal boundary with the
potential for heavy rainfall rates. With additional showers and
thunderstorms expected over recent wet soils, the threat for
isolated flooding concerns will remain elevated for this part of
the country. Therefore a Marginal Risk remain in effect.

Campbell
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